Upgrade to remove ads
Only $35.99/year

Midterm 2

Terms in this set (20)

Correlation
measures strength of linear relationship
Linear prediction:
Estimated as y=a+bx, where 'a' is the intercept which is the value of y when x=0; 'b' is the slope which is the change in y per unit increase in x
Correlation/regression issues:
non-linearity; outliers; avoiding extrapolation in prediction; correlation is not causation.
Risk =
proportion (or percentage) of the time an adverse outcome occurs.
Increased risk =
percentage change from baseline risk to risk of exposed group.
Relative risk =
(Risk for exposed group) / (risk for baseline group).
Odds of an event =
(Chance of event) / (1 - chance of event).
Odds ratio =
(odds of event in one group) / (odds of event in another group).
Simpson's Paradox:
An observed association between two variables can change or even reverse direction when there is another variable that interacts strongly with both variables.
Probabilities (also called "chances") are
numbers between 0 and 1.
If two events are mutually exclusive
then they have no outcomes in common and the probability that one or the other occurs is found by adding the chances.
If two events are independent
then the chance of one thing don't change when you know how the other turned out and the probability that both occur is found by multiplying the chances.
If the ways one event happens are a subset of the ways for another event then its probability can't be
higher
Probabilities of an event can be
simulated by repeating the process many times on a computer and keeping track of the relative frequency of the times that the event happens.
Expectation (long run average) =
sum of values × probabilities.
Law of Large Numbers:
Averages or proportions are likely to be more stable when there are more trials while sums or counts are likely to be more variable. This does not happen by compensation for a bad run of luck since independent trials have no memory.
Sampling distribution of a summary statistic =
the distribution of values you would get if you repeat the basic process over-and-over again.
Normal Approximation:
the sampling distribution of averages or proportions from a large number of independent trials will approximately follow the normal curve.
The standard deviation of a sample proportion is
√p(1−p)/n
The standard deviation of a sample mean is
(population standard deviation)n=σn
Recommended textbook explanations

Probability and Statistics for Engineers and Scientists

9th EditionKeying E. Ye, Raymond H. Myers, Ronald E. Walpole
1,204 explanations

Probability and Statistics for Engineering and the Sciences

8th EditionJay L. Devore
1,232 explanations

Probability and Statistics for Engineers and Scientists, My Lab Statistics Update

9th EditionRonald E. Walpole
1,204 explanations

Introduction to Probability and Statistics

14th EditionBarbara M. Beaver, Robert J. Beaver, William Mendenhall
1,315 explanations